Imaging lens system, image capturing unit and electronic device

ABSTRACT

An imaging lens system includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element. The first lens element with positive refractive power has an object-side surface being convex in a paraxial region thereof. The second lens element has refractive power. The third lens element with refractive power has an image-side surface being concave in a paraxial region thereof. The fourth lens element has refractive power. The fifth lens element with positive refractive power has an object-side surface being convex in a paraxial region thereof. The sixth lens element with negative refractive power has an image-side surface being concave in a paraxial region thereof, wherein the image-side surface of the sixth lens element has at least one convex shape in an off-axis region thereof.

RELATED APPLICATIONS

This application is a continuation patent application of U.S. application Ser. No. 14/526,219, filed on Oct. 28, 2014, which claims priority to Taiwan Application 103129947, filed on Aug. 29, 2014, which is incorporated by reference herein in its entirety.

BACKGROUND

Technical Field

The present disclosure relates to an imaging lens system, an image capturing unit and an electronic device, more particularly to an imaging lens system and an image capturing unit applicable to an electronic device.

Description of Related Art

In recent years, with the popularity of electronic devices having camera functionalities, the demand of miniaturized optical systems has been increasing. The sensor of a conventional optical system is typically a CCD (Charge-Coupled Device) or a CMOS (Complementary Metal-Oxide-Semiconductor) sensor. As the advanced semiconductor manufacturing technologies have allowed the pixel size of sensors to be reduced and compact optical systems have gradually evolved toward the field of higher megapixels, there is an increasing demand for compact optical systems featuring better image quality.

A conventional optical system employed in a portable electronic product mainly adopts a five-element lens structure. Due to the popularity of mobile terminals with high-end specifications, such as smart phones, tablet personal computers and wearable apparatus, the requirements for high resolution and image quality of present compact optical systems increase significantly. However, the conventional optical systems cannot satisfy these requirements of the compact optical systems.

Other conventional compact optical systems with six-element lens structure are developed to enhance resolution and image quality. However, the refractive power is overly concentrated at an object side so as to increase the sensitivity of the optical system. Furthermore, the fifth lens element in the conventional optical system is usually a meniscus lens with high thickness ratio for focusing on an object, whereby it is unfavorable for molding the fifth lens element, which affects the assembling of the optical system.

SUMMARY

According to one aspect of the present disclosure, an imaging lens system includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, and a sixth lens element. The first lens element with positive refractive power has an object-side surface being convex in a paraxial region thereof. The second lens element has positive refractive power. The third lens element with refractive power has an image-side surface being concave in a paraxial region thereof. The fourth lens element has refractive power. The fifth lens element with positive refractive power has an object-side surface being convex in a paraxial region thereof. The sixth lens element with negative refractive power has an image-side surface being concave in a paraxial region thereof, wherein the image-side surface of the sixth lens element has at least one convex shape in an off-axis region thereof, and both of an object-side surface and the image-side surface of the sixth lens element are aspheric. The imaging lens system has a total of six lens elements with refractive power. An air gap in a paraxial region is between any two of the first lens element, the second lens element, the third lens element, the fourth lens element, the fifth lens element and the sixth lens element that are adjacent to each other. When a curvature radius of the object-side surface of the fifth lens element is R9, a curvature radius of an image-side surface of the fifth lens element is R10, a central thickness of the fifth lens element is CT5, a central thickness of the sixth lens element is CT6, an axial distance between the fifth lens element and the sixth lens element is T56, a focal length of the first lens element is f1, a focal length of the second lens element is f2, an axial distance between the object-side surface of the first lens element and an image surface is TTL, a maximum image height of the imaging lens system is ImgH, the following conditions are satisfied: (R9+R10)/(R9−R10)<0.80; 1.35<CT5/(T56+CT6); f2/f1<1.60; and TTL/ImgH<3.0.

According to another aspect of the present disclosure, an imaging lens system includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, and a sixth lens element. The first lens element with positive refractive power has an object-side surface being convex in a paraxial region thereof. The second lens element has positive refractive power. The third lens element has refractive power. The fourth lens element with refractive power has an image-side surface being concave in a paraxial region thereof. The fifth lens element with refractive power has an object-side surface being convex in a paraxial region thereof. The sixth lens element with refractive power has an image-side surface being concave in a paraxial region thereof, wherein the image-side surface of the sixth lens element has at least one convex shape in an off-axis region thereof, and both of an object-side surface and the image-side surface of the sixth lens element are aspheric. The imaging lens system has a total of six lens elements with refractive power. An air gap in a paraxial region is between any two of the first lens element, the second lens element, the third lens element, the fourth lens element, the fifth lens element and the sixth lens element that are adjacent to each other. When a curvature radius of the object-side surface of the fifth lens element is R9, a curvature radius of an image-side surface of the fifth lens element is R10, a central thickness of the fifth lens element is CT5, a central thickness of the sixth lens element is CT6, an axial distance between the fifth lens element and the sixth lens element is T56, an axial distance between the object-side surface of the first lens element and an image surface is TTL, a maximum image height of the imaging lens system is ImgH, the following conditions are satisfied: (R9+R10)/(R9−R10)<0.80; 0.70<CT5/(T56+CT6); and TTL/ImgH<3.0.

According to still another aspect of the present disclosure, an image capturing unit includes the imaging lens system according to the aforementioned aspect and an image sensor, wherein the image sensor is disposed on the image side of the imaging lens system.

According to yet another aspect of the present disclosure, an electronic device includes the image capturing unit according to the aforementioned aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be more fully understood by reading the following detailed description of the embodiments, with reference made to the accompanying drawings as follows:

FIG. 1 is a schematic view of an image capturing unit according to the 1st embodiment of the present disclosure;

FIG. 2 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit according to the 1st embodiment;

FIG. 3 is a schematic view of an image capturing unit according to the 2nd embodiment of the present disclosure;

FIG. 4 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit according to the 2nd embodiment;

FIG. 5 is a schematic view of an image capturing unit according to the 3rd embodiment of the present disclosure;

FIG. 6 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit according to the 3rd embodiment;

FIG. 7 is a schematic view of an image capturing unit according to the 4th embodiment of the present disclosure;

FIG. 8 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit according to the 4th embodiment;

FIG. 9 is a schematic view of an image capturing unit according to the 5th embodiment of the present disclosure;

FIG. 10 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit according to the 5th embodiment;

FIG. 11 is a schematic view of an image capturing unit according to the 6th embodiment of the present disclosure;

FIG. 12 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit according to the 6th embodiment;

FIG. 13 is a schematic view of an image capturing unit according to the 7th embodiment of the present disclosure;

FIG. 14 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit according to the 7th embodiment;

FIG. 15 is a schematic view of an image capturing unit according to the 8th embodiment of the present disclosure;

FIG. 16 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit according to the 8th embodiment;

FIG. 17 shows an electronic device according to one embodiment;

FIG. 18 shows an electronic device according to another embodiment; and

FIG. 19 shows an electronic device according to still another embodiment.

DETAILED DESCRIPTION

An imaging lens system includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element. The imaging lens system has a total of six lens elements with refractive power.

According to the imaging lens system of the present disclosure, an air gap in a paraxial region is arranged between any two of the first lens element, the second lens element, the third lens element, the fourth lens element, the fifth lens element and the sixth lens element that are adjacent to each other, that is, each of the first through sixth lens elements of the imaging lens system is a single and non-cemented lens element. Moreover, the manufacturing process of the cemented lenses is more complex than the non-cemented lenses. In particular, an image-side surface of one lens element and an object-side surface of the following lens element need to have accurate curvature to ensure these two lens elements will be highly cemented. However, during the cementing process, those two lens elements might not be highly cemented due to displacement and it is thereby not favorable for the image quality of the photographing optical lens assembly. Therefore, there is an air gap in a paraxial region between any two of the first lens element, the second lens element, the third lens element, the fourth lens element, the fifth lens element and the sixth lens element that are adjacent to each other in the present disclosure for solving the problem generated by the cemented lens elements.

The first lens element with positive refractive power has an object-side surface being convex in a paraxial region thereof. The first lens element can have an image-side surface being concave in a paraxial region thereof. Therefore, the first lens element provides the imaging lens system with the positive refractive power as the imaging lens system needs to be. Furthermore, it is favorable for correcting the astigmatism of the imaging lens system.

The second lens element with positive refractive power can have an object-side surface being convex in a paraxial region thereof. The object-side surface of the second lens element can have at least one concave shape in an off-axis region thereof. Therefore, it is favorable for avoiding overloading the positive refractive power on the lens element close to the object side so as to reduce the sensitivity of the imaging lens system and correct the aberration of the off-axis.

The third lens element with refractive power has an image-side surface being concave in a paraxial region thereof. Therefore, it is favorable for effectively correcting the aberration of the imaging lens system.

The fourth lens element with refractive power has an image-side surface being concave in a paraxial region thereof. The image-side surface of the fourth lens element can have at least one convex shape in an off-axis region thereof. Therefore, it is favorable for balancing the arrangement of the refractive powers of the imaging lens system and correcting the aberration of the off-axis.

The fifth lens element with positive refractive power has an object-side surface being convex in a paraxial region thereof, and the object-side surface of the fifth lens element can have at least one concave shape in an off-axis region thereof. The fifth lens element can have an image-side surface being convex in a paraxial region thereof, and the image-side surface of the fifth lens element can have at least one concave shape in an off-axis region thereof. Therefore, it is favorable for avoiding the fifth lens element having high thickness ratio and correcting the aberration of the off-axis.

The sixth lens element with negative refractive power can have an object-side surface being concave in a paraxial region thereof. The sixth lens element has an image-side surface being concave in a paraxial region thereof, and the image-side surface of the sixth lens element has at least one convex shape in an off-axis region thereof. Therefore, it is favorable for correcting the aberration of the off-axis.

When a curvature radius of the object-side surface of the fifth lens element is R9, a curvature radius of the image-side surface of the fifth lens element is R10, the following condition is satisfied: (R9+R10)/(R9−R10)<0.80. Therefore, the curvature of the fifth lens element is properly arranged, so that it is favorable for avoiding the fifth lens element having high thickness ratio so as to increase the yield rate. Preferably, the following condition is satisfied: 0<(R9+R10)/(R9−R10)<0.80.

When a central thickness of the fifth lens element is CT5, a central thickness of the sixth lens element is CT6, an axial distance between the fifth lens element and the sixth lens element is T56, the following condition is satisfied: 0.70<CT5/(T56+CT6). Therefore, the lens elements can be tightly arranged, so that it is favorable for reducing a total track length of the imaging lens system so as to keep a compact size. Preferably, the following condition is satisfied: 1.35<CT5/(T56+CT6). More preferably, the following condition is satisfied: 1.60<CT5/(T56+CT6)<3.0.

When a focal length of the first lens element is f1, a focal length of the second lens element is f2, the following condition is satisfied: f2/f1<1.60. Therefore, it is favorable for avoiding overloading the refractive power on the lens element close to the object side so as to reduce the sensitivity of the imaging lens system.

When an axial distance between the object-side surface of the first lens element and an image surface is TTL, a maximum image height of the imaging lens system (half of a diagonal length of an effective photosensitive area of an image sensor) is ImgH, the following condition is satisfied: TTL/ImgH<3.0. Therefore, it is favorable for keeping the imaging lens system compact so as to be equipped in an electronic device.

When a focal length of the imaging lens system is f, a focal length of the fifth lens element is f5, a focal length of the sixth lens element is f6, the following condition is satisfied: 3.0<|f/f5|+|f/f6|<7.5. Therefore, it is favorable for balancing the arrangement of the refractive powers of the fifth lens element and the sixth lens element so as to reduce the sensitivity of the imaging lens system.

When the focal length of the imaging lens system is f, a curvature radius of the object-side surface of the sixth lens element is R11, a curvature radius of the image-side surface of the sixth lens element is R12, the following condition is satisfied: 4.5<(f/R12)−(f/R11)<6.0. Therefore, it is favorable for the principal point of the imaging lens system being positioned away from the image side of the imaging lens system and reducing a back focal length of the imaging lens system.

When an axial distance between the object-side surface of the first lens element and the image-side surface of the third lens element is Dr1r6, an axial distance between the image-side surface of the third lens element and the object-side surface of the fifth lens element is Dr6r9, the following condition is satisfied: 0.7<Dr1r6/Dr6r9<1.5. Therefore, it is favorable for adjusting the axial distances between any two adjacent lens elements so as to reduce the total track length of the imaging lens system. Preferably, the following condition is satisfied: 0.8<Dr1 r6/Dr6r9<1.2.

When an axial distance between the object-side surface of the first lens element and the image-side surface of the sixth lens element is TD, an entrance pupil diameter of the imaging lens system is EPD, the following condition is satisfied: TD/EPD<2.50. Therefore, it is favorable for providing sufficient amount of incident light and keeping the imaging lens system compact.

When the focal length of the imaging lens system is f, a curvature radius of an object-side surface of the fourth lens element is R7, a curvature radius of the image-side surface of the fourth lens element is R8, the following condition is satisfied: |f/R7|+|f/R8|<0.80. Therefore, it is favorable for correcting the astigmatism of the imaging lens system and reducing the sensitivity of the imaging lens system.

When an axial distance between the first lens element and the second lens element is T12, an axial distance between the second lens element and the third lens element is T23, an axial distance between the third lens element and the fourth lens element is T34, an axial distance between the fourth lens element and the fifth lens element is T45, the axial distance between the fifth lens element and the sixth lens element is T56, the following condition is satisfied: 1.5<(T34+T45)/(T12+T23+T56). Therefore, it is favorable for adjusting the axial distances between any two adjacent lens elements so as to reduce the total track length of the imaging lens system, thereby keeping the imaging lens system compact.

According to the imaging lens system of the present disclosure, an aperture stop can be configured as a front stop or a middle stop. A front stop disposed between an imaged object and the first lens element can provide a longer distance between an exit pupil of the imaging lens system and the image surface and thereby improves the image-sensing efficiency of an image sensor. A middle stop disposed between the first lens element and the image surface is favorable for enlarging the field of view of the imaging lens system and thereby provides a wider field of view for the same.

According to the imaging lens system of the present disclosure, the lens elements thereof can be made of glass or plastic material. When the lens elements are made of glass material, the distribution of the refractive power of the imaging lens system may be more flexible to design. When the lens elements are made of plastic material, the manufacturing cost can be effectively reduced. Furthermore, surfaces of each lens element can be arranged to be aspheric, since the aspheric surface of the lens element is easy to form a shape other than spherical surface so as to have more controllable variables for eliminating the aberration thereof, and to further decrease the required number of the lens elements. Therefore, the total track length of the imaging lens system can also be reduced.

According to the imaging lens system of the present disclosure, each of an object-side surface and an image-side surface has a paraxial region and an off-axis region. The paraxial region refers to the region of the surface where light rays travel close to the optical axis, and the off-axis region refers to the region of the surface away from the paraxial region. Particularly, when the lens element has a convex surface, it indicates that the surface is convex in the paraxial region thereof; when the lens element has a concave surface, it indicates that the surface is concave in the paraxial region thereof. Moreover, when a region of refractive power or focus of a lens element is not defined, it indicates that the region of refractive power or focus of the lens element is in the paraxial region thereof. According to the imaging lens system of the present disclosure, an image surface of the imaging lens system, based on the corresponding image sensor, can be flat or curved, especially a curved surface being concave facing towards the object side of the imaging lens system.

According to the imaging lens system of the present disclosure, the imaging lens system can include at least one stop, such as an aperture stop, a glare stop or a field stop. Said glare stop or said field stop is set for eliminating the stray light and thereby improving the image quality thereof.

According to the present disclosure, an image capturing unit is provided. The image capturing unit includes the imaging lens system according to the aforementioned imaging lens system of the present disclosure, and an image sensor, wherein the image sensor is disposed on the image side of the aforementioned imaging lens system, that is, the image sensor can be disposed on or near an image surface of the aforementioned imaging lens system. In some embodiments, the image capturing unit can further include a barrel member, a holding member or a combination thereof.

In FIG. 17, FIG. 18 and FIG. 19, an image capturing device 10 may be installed in, but not limited to, an electronic device, including a smart phone (FIG. 17), a tablet personal computer (FIG. 18) or a wearable device (FIG. 19). The three exemplary figures of different kinds of electronic device are only exemplary for showing the image capturing device of present disclosure installing in an electronic device and is not limited thereto. In some embodiments, the electronic device can further include, but not limited to, a display unit, a control unit, a storage unit, a random access memory unit (RAM), a read only memory unit (ROM) or a combination thereof.

According to the imaging lens system of the present disclosure, the imaging lens system can be optionally applied to moving focus optical systems. Furthermore, the imaging lens system is featured with good capability in the correction of aberration and high image quality, and can be applied to 3D (three-dimensional) image capturing applications, in products such as digital cameras, mobile devices, digital tablets, wearable devices, smart televisions, wireless monitoring devices, motion sensing input devices, driving recorders, rear view cameras and other electronic imaging devices. According to the above description of the present disclosure, the following specific embodiments are provided for further explanation.

1st Embodiment

FIG. 1 is a schematic view of an image capturing unit according to the 1st embodiment of the present disclosure. FIG. 2 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit according to the 1st embodiment. In FIG. 1, the image capturing unit includes the imaging lens system (its reference numeral is omitted) of the present disclosure and an image sensor 190. The imaging lens system includes, in order from an object side to an image side, a first lens element 110, an aperture stop 100, a second lens element 120, a third lens element 130, a fourth lens element 140, a fifth lens element 150, a sixth lens element 160, an IR-cut filter 170 and an image surface 180, wherein the imaging lens system has a total of six lens elements (110-160) with refractive power. There is an air gap in a paraxial region between any two of the first lens element 110, the second lens element 120, the third lens element 130, the fourth lens element 140, the fifth lens element 150 and the sixth lens element 160 that are adjacent to each other.

The first lens element 110 with positive refractive power has an object-side surface 111 being convex in a paraxial region thereof and an image-side surface 112 being concave in a paraxial region thereof. The first lens element 110 is made of plastic material and has the object-side surface 111 and the image-side surface 112 being both aspheric.

The second lens element 120 with positive refractive power has an object-side surface 121 being convex in a paraxial region thereof and an image-side surface 122 being convex in a paraxial region thereof. The object-side surface 121 of the second lens element 120 has at least one concave shape in an off-axis region thereof. The second lens element 120 is made of plastic material and has the object-side surface 121 and the image-side surface 122 being both aspheric.

The third lens element 130 with negative refractive power has an object-side surface 131 being convex in a paraxial region thereof and an image-side surface 132 being concave in a paraxial region thereof. The third lens element 130 is made of glass material and has the object-side surface 131 and the image-side surface 132 being both aspheric.

The fourth lens element 140 with negative refractive power has an object-side surface 141 being concave in a paraxial region thereof and an image-side surface 142 being convex in a paraxial region thereof. The fourth lens element 140 is made of plastic material and has the object-side surface 141 and the image-side surface 142 being both aspheric.

The fifth lens element 150 with positive refractive power has an object-side surface 151 being convex in a paraxial region thereof and an image-side surface 152 being convex in a paraxial region thereof. The object-side surface 151 of the fifth lens element 150 has at least one concave shape in an off-axis region thereof. The image-side surface 152 of the fifth lens element 150 has at least one concave shape in an off-axis region thereof. The fifth lens element 150 is made of plastic material and has the object-side surface 151 and the image-side surface 152 being both aspheric.

The sixth lens element 160 with negative refractive power has an object-side surface 161 being concave in a paraxial region thereof and an image-side surface 162 being concave in a paraxial region thereof. The image-side surface 162 of the sixth lens element 160 has at least one convex shape in an off-axis region thereof. The sixth lens element 160 is made of plastic material and has the object-side surface 161 and the image-side surface 162 being both aspheric.

The IR-cut filter 170 is made of glass and located between the sixth lens element 160 and the image surface 180, and will not affect the focal length of the imaging lens system. The image sensor 190 is disposed on or near the image surface 180 of the imaging lens system.

The equation of the aspheric surface profiles of the aforementioned lens elements of the 1st embodiment is expressed as follows:

${{X(Y)} = {{\left( {Y^{2}\text{/}R} \right)\text{/}\left( {1 + {{sqrt}\left( {1 - {\left( {1 + k} \right) \times \left( {Y\text{/}R} \right)^{2}}} \right)}} \right)} + {\sum\limits_{i}{({Ai}) \times \left( Y^{i} \right)}}}},$ where,

X is the relative distance between a point on the aspheric surface spaced at a distance Y from an optical axis and the tangential plane at the aspheric surface vertex on the optical axis;

Y is the vertical distance from the point on the aspheric surface to the optical axis;

R is the curvature radius;

k is the conic coefficient; and

Ai is the i-th aspheric coefficient, and in the embodiments, i may be, but is not limited to, 4, 6, 8, 10, 12, 14 and 16.

In the imaging lens system of the image capturing unit according to the 1st embodiment, when a focal length of the imaging lens system is f, an f-number of the imaging lens system is Fno, and half of a maximal field of view of the imaging lens system is HFOV, these parameters have the following values: f=4.81 mm; Fno=2.22; and HFOV=37.3 degrees.

When a central thickness of the fifth lens element 150 is CT5, a central thickness of the sixth lens element 160 is CT6, an axial distance between the fifth lens element 150 and the sixth lens element 160 is T56, the following condition is satisfied: CT5/(T56+CT6)=1.41.

When an axial distance between the first lens element 110 and the second lens element 120 is T12, an axial distance between the second lens element 120 and the third lens element 130 is T23, an axial distance between the third lens element 130 and the fourth lens element 140 is T34, an axial distance between the fourth lens element 140 and the fifth lens element 150 is T45, the axial distance between the fifth lens element 150 and the sixth lens element 160 is T56, the following condition is satisfied: (T34+T45)/(T12+T23+T56)=2.85.

When an axial distance between the object-side surface 111 of the first lens element 110 and the image-side surface 132 of the third lens element 130 is Dr1 r6, an axial distance between the image-side surface 132 of the third lens element 130 and the object-side surface 151 of the fifth lens element 150 is Dr6r9, the following condition is satisfied: Dr1 r6/Dr6r9=0.90.

When a curvature radius of the object-side surface 151 of the fifth lens element 150 is R9, a curvature radius of the image-side surface 152 of the fifth lens element 150 is R10, the following condition is satisfied: (R9+R10)/(R9−R10)=0.52.

When a focal length of the imaging lens system is f, a curvature radius of the object-side surface 141 of the fourth lens element 140 is R7, a curvature radius of the image-side surface 142 of the fourth lens element 140 is R8, the following condition is satisfied: |f/R7|+|f/R81=0.25.

When the focal length of the imaging lens system is f, a curvature radius of the object-side surface 161 of the sixth lens element 160 is R11, a curvature radius of the image-side surface 162 of the sixth lens element 160 is R12, the following condition is satisfied: (f/R12)−(f/R11)=4.80.

When a focal length of the first lens element 110 is f1, a focal length of the second lens element 120 is f2, the following condition is satisfied: f2/f1=0.24.

When the focal length of the imaging lens system is f, a focal length of the fifth lens element 150 is f5, a focal length of the sixth lens element 160 is f6, the following condition is satisfied: |f/f51+|f/f61=4.77.

When an axial distance between the object-side surface 111 of the first lens element 110 and the image surface 180 is TTL, a maximum image height of the imaging lens system is ImgH, the following condition is satisfied: TTL/ImgH=1.55.

When an axial distance between the object-side surface 111 of the first lens element 110 and the image-side surface 162 of the sixth lens element 160 is TD, an entrance pupil diameter of the imaging lens system is EPD, the following condition is satisfied: TD/EPD=2.08.

The detailed optical data of the 1st embodiment are shown in Table 1 and the aspheric surface data are shown in Table 2 below.

TABLE 1 1st Embodiment f = 4.81 mm, Fno = 2.22, HFOV = 37.3 deg. Focal Surface # Curvature Radius Thickness Material Index Abbe # Length 0 Object Plano Infinity 1 Lens 1 2.196 (ASP) 0.397 Plastic 1.544 55.9 15.53 2 2.778 (ASP) 0.088 3 Ape. Stop Plano 0.018 4 Lens 2 2.376 (ASP) 0.509 Plastic 1.544 55.9 3.66 5 −11.441 (ASP) 0.051 6 Lens 3 25.261 (ASP) 0.300 Glass 1.844 24.8 −4.78 7 3.461 (ASP) 0.499 8 Lens 4 −23.083 (ASP) 0.430 Plastic 1.634 23.8 −45.66 9 −114.780 (ASP) 0.589 10 Lens 5 4.879 (ASP) 0.952 Plastic 1.544 55.9 2.26 11 −1.529 (ASP) 0.225 12 Lens 6 −4.003 (ASP) 0.451 Plastic 1.535 55.7 −1.82 13 1.336 (ASP) 0.750 14 IR-cut filter Plano 0.210 Glass 1.517 64.2 — 15 Plano 0.401 16 Image Plano — Note: Reference wavelength is 587.6 nm (d-line),

TABLE 2 Aspheric Coefficients Surface # 1 2 4 5 6 7 k = −4.8320E−01 −7.7152E+00 −1.0903E+01 −8.7367E+01 −9.0000E+01 5.6179E+00 A4 = −2.5293E−02 −1.1170E−01 −4.5821E−02 −9.7909E−02 −4.7122E−02 −3.3087E−02 A6 = 4.0536E−03 1.6113E−02 −1.0036E−01 1.2639E−01 1.8346E−01 1.0157E−01 A8 = −1.6158E−02 1.5387E−02 1.4642E−01 −1.1837E−01 −2.2669E−01 −1.5632E−01 A10 = 4.0160E−03 6.2140E−04 −5.4444E−02 4.5895E−02 1.0651E−01 1.0332E−01 A12 = 1.6293E−06 −3.0737E−03 6.0031E−04 −7.6088E−03 −1.2956E−02 −3.5110E−02 A14 = −3.3851E−10 1.1045E−10 7.8686E−11 −1.5643E−10 −8.8952E−04 5.8677E−03 A16 = −2.8676E−11 7.7362E−12 6.0603E−12 −1.2089E−11 1.6010E−11 −1.4141E−11 Surface # 8 9 10 11 12 13 k = −8.8459E+01 9.0000E+01 2.1494E+00 −9.6844E+00 2.5786E−01 −8.2314E+00 A4 = −1.2196E−01 −1.3205E−01 −2.0598E−02 −1.5606E−02 −8.9382E−03 −3.1051E−02 A6 = 6.1199E−02 6.3427E−02 1.9422E−02 1.0035E−01 3.5669E−02 9.7672E−03 A8 = −3.2032E−02 −4.0686E−02 −1.2558E−02 −6.3732E−02 −2.2725E−02 −2.8101E−03 A10 = 2.0845E−02 2.2900E−02 2.1070E−03 1.8924E−02 7.6103E−03 4.5937E−04 A12 = −3.8188E−03 −4.4894E−03 1.2014E−04 −3.0040E−03 −1.3438E−03 −3.8165E−05 A14 = −1.1808E−03 1.3575E−04 −6.4315E−05 2.4339E−04 1.1709E−04 1.3882E−06 A16 = −3.0852E−10 −3.6945E−05 4.7448E−06 −7.8738E−06 −3.9683E−06 −1.3122E−08

In Table 1, the curvature radius, the thickness and the focal length are shown in millimeters (mm). Surface numbers 0-16 represent the surfaces sequentially arranged from the object-side to the image-side along the optical axis. In Table 2, k represents the conic coefficient of the equation of the aspheric surface profiles. A4-A16 represent the aspheric coefficients ranging from the 4th order to the 16th order. The tables presented below for each embodiment are the corresponding schematic parameter and aberration curves, and the definitions of the tables are the same as Table 1 and Table 2 of the 1st embodiment. Therefore, an explanation in this regard will not be provided again.

2nd Embodiment

FIG. 3 is a schematic view of an image capturing unit according to the 2nd embodiment of the present disclosure. FIG. 4 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit according to the 2nd embodiment. In FIG. 3, the image capturing unit includes the imaging lens system (its reference numeral is omitted) of the present disclosure and an image sensor 290. The imaging lens system includes, in order from an object side to an image side an aperture stop 200, a first lens element 210, a second lens element 220, a third lens element 230, a fourth lens element 240, a fifth lens element 250, a sixth lens element 260, an IR-cut filter 270 and an image surface 280, wherein the imaging lens system has a total of six lens elements (210-260) with refractive power. There is an air gap in a paraxial region between any two of the first lens element 210, the second lens element 220, the third lens element 230, the fourth lens element 240, the fifth lens element 250 and the sixth lens element 260 that are adjacent to each other.

The first lens element 210 with positive refractive power has an object-side surface 211 being convex in a paraxial region thereof and an image-side surface 212 being concave in a paraxial region thereof. The first lens element 210 is made of plastic material and has the object-side surface 211 and the image-side surface 212 being both aspheric.

The second lens element 220 with positive refractive power has an object-side surface 221 being convex in a paraxial region thereof and an image-side surface 222 being concave in a paraxial region thereof. The object-side surface 221 of the second lens element 220 has at least one concave shape in an off-axis region thereof. The second lens element 220 is made of plastic material and has the object-side surface 221 and the image-side surface 222 being both aspheric.

The third lens element 230 with negative refractive power has an object-side surface 231 being concave in a paraxial region thereof and an image-side surface 232 being concave in a paraxial region thereof. The third lens element 230 is made of plastic material and has the object-side surface 231 and the image-side surface 232 being both aspheric.

The fourth lens element 240 with positive refractive power has an object-side surface 241 being convex in a paraxial region thereof and an image-side surface 242 being concave in a paraxial region thereof. The image-side surface 242 of the fourth lens element 240 has at least one convex shape in an off-axis region thereof. The fourth lens element 240 is made of plastic material and has the object-side surface 241 and the image-side surface 242 being both aspheric.

The fifth lens element 250 with positive refractive power has an object-side surface 251 being convex in a paraxial region thereof and an image-side surface 252 being convex in a paraxial region thereof. The object-side surface 251 of the fifth lens element 250 has at least one concave shape in an off-axis region thereof. The image-side surface 252 of the fifth lens element 250 has at least one concave shape in an off-axis region thereof. The fifth lens element 250 is made of plastic material and has the object-side surface 251 and the image-side surface 252 being both aspheric.

The sixth lens element 260 with negative refractive power has an object-side surface 261 being concave in a paraxial region thereof and an image-side surface 262 being concave in a paraxial region thereof. The image-side surface 262 of the sixth lens element 260 has at least one convex shape in an off-axis region thereof. The sixth lens element 260 is made of plastic material and has the object-side surface 261 and the image-side surface 262 being both aspheric.

The IR-cut filter 270 is made of glass and located between the sixth lens element 260 and the image surface 280, and will not affect the focal length of the imaging lens system. The image sensor 290 is disposed on or near the image surface 280 of the imaging lens system.

The detailed optical data of the 2nd embodiment are shown in Table 3 and the aspheric surface data are shown in Table 4 below.

TABLE 3 2nd Embodiment f = 4.78 mm, Fno = 1.87, HFOV = 37.4 deg. Curvature Focal Surface # Radius Thickness Material Index Abbe # Length 0 Object Plano Infinity 1 Ape. Stop Plano −0.399   2 Lens 1 2.089 (ASP) 0.534 Plastic 1.544 55.9 11.29 3 2.879 (ASP) 0.125 4 Lens 2 2.641 (ASP) 0.498 Plastic 1.544 55.9 4.97 5 108.327 (ASP) 0.050 6 Lens 3 −41.588 (ASP) 0.307 Plastic 1.650 21.5 −6.44 7 4.672 (ASP) 0.452 8 Lens 4 8.525 (ASP) 0.396 Plastic 1.639 23.5 478.23 9 8.610 (ASP) 0.585 10 Lens 5 5.925 (ASP) 1.152 Plastic 1.544 55.9 2.30 11 −1.481 (ASP) 0.140 12 Lens 6 −4.243 (ASP) 0.492 Plastic 1.544 55.9 −1.83 13 1.359 (ASP) 0.600 14 IR-cut filter Plano 0.300 Glass 1.517 64.2 — 15 Plano 0.357 16 Image Plano — Note: Reference wavelength is 587.6 nm (d-line).

TABLE 4 Aspheric Coefficients Surface # 2 3 4 5 6 7 k = 2.4189E−01 −2.8203E+00 −1.5018E+01 −8.8779E+01 9.0000E+01 8.6183E+00 A4 = −1.3585E−02 −8.2237E−02 −1.6670E−02 −1.3140E−01 −5.8722E−02 5.5596E−04 A6 = 1.3340E−03 4.8439E−03 −1.2793E−01 1.5366E−01 2.1826E−01 9.9306E−02 A8 = −2.9035E−03 8.9557E−03 1.2202E−01 −1.2304E−01 −2.3697E−01 −1.5345E−01 A10 = −3.7414E−05 1.9917E−03 −3.8992E−02 4.5735E−02 9.4868E−02 9.4768E−02 A12 = 1.5342E−04 −1.5280E−03 2.0959E−03 −7.0274E−03 −4.0783E−03 −2.4645E−02 A14 = 7.1146E−06 7.6787E−06 8.7312E−06 −1.2364E−05 −5.1825E−03 1.2156E−03 A16 = 2.7019E−06 6.9219E−06 1.5208E−07 −2.3904E−05 7.8428E−04 5.2802E−04 Surface # 8 9 10 11 12 13 k = 1.2019E+01 1.2315E+01 6.7186E−01 −8.9684E+00 1.0068E+00 −8.2715E+00 A4 = −1.2024E−01 −1.2415E−01 −2.2184E−02 4.6252E−03 1.3629E−02 −2.7660E−02 A6 = 1.3344E−01 9.9722E−02 2.2355E−02 3.7467E−02 −1.4556E−02 4.3893E−03 A8 = −1.8315E−01 −1.0513E−01 −1.8900E−02 −1.9350E−02 1.1582E−02 −9.5287E−05 A10 = 1.8380E−01 8.0817E−02 7.4009E−03 4.1106E−03 −3.5636E−03 −1.5529E−04 A12 = −1.1444E−01 −3.8688E−02 −2.0625E−03 −3.9329E−04 5.6019E−04 3.2251E−05 A14 = 3.9469E−02 1.0683E−02 3.5969E−04 9.3389E−06 −4.5472E−05 −2.5503E−06 A16 = −5.7245E−03 −1.2742E−03 −2.5866E−05 5.3251E−07 1.5154E−06 7.1544E−08

In the 2nd embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in the following table are the same as those stated in the 1st embodiment with corresponding values for the 2nd embodiment, so an explanation in this regard will not be provided again.

Moreover, these parameters can be calculated from Table 3 and Table 4 as the following values and satisfy the following conditions:

2nd Embodiment f [mm] 4.78 |f/R7| + |f/R8| 1.12 Fno 1.87 (f/R12) − (f/R11) 4.64 HFOV [deg.] 37.4 f2/f1 0.44 CT5/(T56 + CT6) 1.82 |f/f5| + |f/f6| 4.69 (T34 + T45)/(T12 + T23 + T56) 3.29 TTL/ImgH 1.57 Dr1r6/Dr6r9 1.06 TD/EPD 1.85 (R9 + R10)/(R9 − R10) 0.60

3rd Embodiment

FIG. 5 is a schematic view of an image capturing unit according to the 3rd embodiment of the present disclosure. FIG. 6 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit according to the 3rd embodiment. In FIG. 5, the image capturing unit includes the imaging lens system (its reference numeral is omitted) of the present disclosure and an image sensor 390. The imaging lens system includes, in order from an object side to an image side, an aperture stop 300, a first lens element 310, a second lens element 320, a third lens element 330, a fourth lens element 340, a fifth lens element 350, a sixth lens element 360, an IR-cut filter 370 and an image surface 380, wherein the imaging lens system has a total of six lens elements (310-360) with refractive power. There is an air gap in a paraxial region between any two of the first lens element 310, the second lens element 320, the third lens element 330, the fourth lens element 340, the fifth lens element 350 and the sixth lens element 360 that are adjacent to each other.

The first lens element 310 with positive refractive power has an object-side surface 311 being convex in a paraxial region thereof and an image-side surface 312 being concave in a paraxial region thereof. The first lens element 310 is made of plastic material and has the object-side surface 311 and the image-side surface 312 being both aspheric.

The second lens element 320 with positive refractive power has an object-side surface 321 being convex in a paraxial region thereof and an image-side surface 322 being convex in a paraxial region thereof. The object-side surface 321 of the second lens element 320 has at least one concave shape in an off-axis region thereof. The second lens element 320 is made of plastic material and has the object-side surface 321 and the image-side surface 322 being both aspheric.

The third lens element 330 with negative refractive power has an object-side surface 331 being concave in a paraxial region thereof and an image-side surface 332 being concave in a paraxial region thereof. The third lens element 330 is made of plastic material and has the object-side surface 331 and the image-side surface 332 being both aspheric.

The fourth lens element 340 with negative refractive power has an object-side surface 341 being convex in a paraxial region thereof and an image-side surface 342 being concave in a paraxial region thereof. The image-side surface 342 of the fourth lens element 340 has at least one convex shape in an off-axis region thereof. The fourth lens element 340 is made of plastic material and has the object-side surface 341 and the image-side surface 342 being both aspheric.

The fifth lens element 350 with positive refractive power has an object-side surface 351 being convex in a paraxial region thereof and an image-side surface 352 being convex in a paraxial region thereof. The object-side surface 351 of the fifth lens element 350 has at least one concave shape in an off-axis region thereof. The image-side surface 352 of the fifth lens element 350 has at least one concave shape in an off-axis region thereof. The fifth lens element 350 is made of plastic material and has the object-side surface 351 and the image-side surface 352 being both aspheric.

The sixth lens element 360 with negative refractive power has an object-side surface 361 being concave in a paraxial region thereof and an image-side surface 362 being concave in a paraxial region thereof. The image-side surface 362 of the sixth lens element 360 has at least one convex shape in an off-axis region thereof. The sixth lens element 360 is made of plastic material and has the object-side surface 361 and the image-side surface 362 being both aspheric.

The IR-cut filter 370 is made of glass and located between the sixth lens element 360 and the image surface 380, and will not affect the focal length of the imaging lens system. The image sensor 390 is disposed on or near the image surface 380 of the imaging lens system.

The detailed optical data of the 3rd embodiment are shown in Table 5 and the aspheric surface data are shown in Table 6 below.

TABLE 5 3rd Embodiment f = 4.77 mm, Fno = 2.05, HFOV = 37.5 deg. Curvature Focal Surface # Radius Thickness Material Index Abbe # Length 0 Object Plano Infinity 1 Ape. Stop Plano −0.310   2 Lens 1 2.031 (ASP) 0.445 Plastic 1.544 55.9 9.55 3 3.077 (ASP) 0.118 4 Lens 2 3.327 (ASP) 0.540 Plastic 1.544 55.9 4.61 5 −9.644 (ASP) 0.050 6 Lens 3 −28.208 (ASP) 0.338 Plastic 1.639 23.5 −5.32 7 3.880 (ASP) 0.412 8 Lens 4 10.417 (ASP) 0.423 Plastic 1.639 23.5 −155.93 9 9.282 (ASP) 0.512 10 Lens 5 6.045 (ASP) 1.143 Plastic 1.544 55.9 2.09 11 −1.308 (ASP) 0.114 12 Lens 6 −4.518 (ASP) 0.450 Plastic 1.544 55.9 −1.68 13 1.183 (ASP) 0.600 14 IR-cut filter Plano 0.210 Glass 1.517 64.2 — 15 Plano 0.513 16 Image Plano — Note: Reference wavelength is 587.6 nm (d-line).

TABLE 6 Aspheric Coefficients Surface # 2 3 4 5 6 7 k = 3.7656E−02 −4.0572E+00 −2.5726E+01 −7.6552E+00 −9.0000E+01 5.5140E+00 A4 = −1.7569E−02 −9.2509E−02 −4.1328E−02 −1.1402E−01 −6.5178E−02 −2.5542E−02 A6 = 4.3248E−04 −3.3325E−03 −1.1159E−01 1.4620E−01 1.9581E−01 9.3731E−02 A8 = −5.5881E−03 1.6583E−02 1.3464E−01 −1.2320E−01 −2.3639E−01 −1.4563E−01 A10 = −8.2100E−04 4.4011E−03 −4.2086E−02 4.6031E−02 1.0653E−01 1.0072E−01 A12 = — −3.0768E−03 6.0260E−04 −7.6147E−03 −1.2948E−02 −3.5114E−02 A14 = — — — — −8.8952E−04 5.8677E−03 Surface # 8 9 10 11 12 13 k = −8.7331E+01 −3.9939E+01 5.8643E+00 −8.3160E+00 1.1301E+00 −8.2477E+00 A4 = −1.0078E−01 −1.1949E−01 −2.8447E−02 8.3327E−03 −1.2301E−02 −4.2869E−02 A6 = 7.0640E−02 7.0091E−02 1.1764E−02 3.3965E−02 −8.1138E−04 1.2146E−02 A8 = −3.6773E−02 −4.3615E−02 −1.0226E−02 −2.2370E−02 4.7591E−03 −2.7789E−03 A10 = 1.6036E−02 2.1956E−02 1.9102E−03 6.2791E−03 −1.4488E−03 4.1577E−04 A12 = −3.7130E−03 −4.9155E−03 5.1862E−06 −9.2701E−04 1.9505E−04 −3.7929E−05 A14 = — 3.0277E−04 −1.8662E−05 6.9961E−05 −1.2903E−05 1.9015E−06 A16 = — — — −2.1281E−06 3.4924E−07 −3.9757E−08

In the 3rd embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in the following table are the same as those stated in the 1st embodiment with corresponding values for the 3rd embodiment, so an explanation in this regard will not be provided again.

Moreover, these parameters can be calculated from Table 5 and Table 6 as the following values and satisfy the following conditions:

3rd Embodiment f [mm] 4.77 |f/R7| + |f/R8| 0.97 Fno 2.05 (f/R12) − (f/R11) 5.09 HFOV [deg.] 37.5 f2/f1 0.48 CT5/(T56 + CT6) 2.03 |f/f5| + |f/f6| 5.12 (T34 + T45)/(T12 + T23 + T56) 3.28 TTL/ImgH 1.55 Dr1r6/Dr6r9 1.11 TD/EPD 1.95 (R9 + R10)/(R9 − R10) 0.64

4th Embodiment

FIG. 7 is a schematic view of an image capturing unit according to the 4th embodiment of the present disclosure. FIG. 8 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit according to the 4th embodiment. In FIG. 7, the image capturing unit includes the imaging lens system (its reference numeral is omitted) of the present disclosure and an image sensor 490. The imaging lens system includes, in order from an object side to an image side, an aperture stop 400, a first lens element 410, a second lens element 420, a third lens element 430, a fourth lens element 440, a fifth lens element 450, a sixth lens element 460, an IR-cut filter 470 and an image surface 480, wherein the imaging lens system has a total of six lens elements (410-460) with refractive power. There is an air gap in a paraxial region between any two of the first lens element 410, the second lens element 420, the third lens element 430, the fourth lens element 440, the fifth lens element 450 and the sixth lens element 460 that are adjacent to each other.

The first lens element 410 with positive refractive power has an object-side surface 411 being convex in a paraxial region thereof and an image-side surface 412 being concave in a paraxial region thereof. The first lens element 410 is made of plastic material and has the object-side surface 411 and the image-side surface 412 being both aspheric.

The second lens element 420 with positive refractive power has an object-side surface 421 being convex in a paraxial region thereof and an image-side surface 422 being convex in a paraxial region thereof. The object-side surface 421 of the second lens element 420 has at least one concave shape in an off-axis region thereof. The second lens element 420 is made of plastic material and has the object-side surface 421 and the image-side surface 422 being both aspheric.

The third lens element 430 with negative refractive power has an object-side surface 431 being concave in a paraxial region thereof and an image-side surface 432 being concave in a paraxial region thereof. The third lens element 430 is made of plastic material and has the object-side surface 431 and the image-side surface 432 being both aspheric.

The fourth lens element 440 with positive refractive power has an object-side surface 441 being convex in a paraxial region thereof and an image-side surface 442 being concave in a paraxial region thereof. The image-side surface 442 of the fourth lens element 440 has at least one convex shape in an off-axis region thereof. The fourth lens element 440 is made of plastic material and has the object-side surface 441 and the image-side surface 442 being both aspheric.

The fifth lens element 450 with positive refractive power has an object-side surface 451 being convex in a paraxial region thereof and an image-side surface 452 being convex in a paraxial region thereof. The object-side surface 451 of the fifth lens element 450 has at least one concave shape in an off-axis region thereof. The image-side surface 452 of the fifth lens element 450 has at least one concave shape in an off-axis region thereof. The fifth lens element 450 is made of plastic material and has the object-side surface 451 and the image-side surface 452 being both aspheric.

The sixth lens element 460 with negative refractive power has an object-side surface 461 being concave in a paraxial region thereof and an image-side surface 462 being concave in a paraxial region thereof. The image-side surface 462 of the sixth lens element 460 has at least one convex shape in an off-axis region thereof. The sixth lens element 460 is made of plastic material and has the object-side surface 461 and the image-side surface 462 being both aspheric.

The IR-cut filter 470 is made of glass and located between the sixth lens element 460 and the image surface 480, and will not affect the focal length of the imaging lens system. The image sensor 490 is disposed on or near the image surface 480 of the imaging lens system.

The detailed optical data of the 4th embodiment are shown in Table 7 and the aspheric surface data are shown in Table 8 below.

TABLE 7 4th Embodiment f = 4.94 mm, Fno = 2.05, HFOV = 36.9 deg. Curvature Focal Surface # Radius Thickness Material Index Abbe # Length 0 Object Plano Infinity 1 Ape. Stop Plano −0.357   2 Lens 1 1.977 (ASP) 0.456 Plastic 1.544 55.9 8.48 3 3.178 (ASP) 0.161 4 Lens 2 3.306 (ASP) 0.510 Plastic 1.544 55.9 4.66 5 −10.308 (ASP) 0.052 6 Lens 3 −22.625 (ASP) 0.313 Plastic 1.639 23.5 −4.87 7 3.626 (ASP) 0.375 8 Lens 4 9.179 (ASP) 0.648 Plastic 1.639 23.5 107.95 9 10.296 (ASP) 0.541 10 Lens 5 7.234 (ASP) 1.054 Plastic 1.544 55.9 2.12 11 −1.301 (ASP) 0.091 12 Lens 6 −4.435 (ASP) 0.440 Plastic 1.544 55.9 −1.65 13 1.167 (ASP) 0.600 14 IR-cut filter Plano 0.210 Glass 1.517 64.2 — 15 Plano 0.511 16 Image Plano — Note: Reference wavelength is 587.6 nm (d-line). Effective radius of the image-side surface of the second lens element (surface 5) is 1.260 mm.

TABLE 8 Aspheric Coefficients Surface # 2 3 4 5 6 7 k = 1.5659E−01 −1.0804E+00 −3.4756E+01 −1.0122E+01 −8.8508E+01 5.4357E+00 A4 = −1.5339E−02 −7.4793E−02 4.1811E−03 −1.0870E−01 −4.8686E−02 −2.3833E−02 A6 = −2.0336E−03 −6.9664E−03 −1.6300E−01 1.2085E−01 1.9409E−01 9.8953E−02 A8 = −3.8295E−03 1.5280E−02 1.6631E−01 −9.7651E−02 −2.4427E−01 −1.5385E−01 A10 = — — −5.9939E−02 3.8683E−02 1.2681E−01 1.0265E−01 A12 = — — 6.1930E−03 −7.3032E−03 −2.6130E−02 −3.2866E−02 A14 = — — — — 1.5635E−03 4.9648E−03 Surface # 8 9 10 11 12 13 k = −1.9890E+00 −3.9939E+01 5.2418E+00 −8.3571E+00 1.1967E+00 −8.5250E+00 A4 = −7.4565E−02 −6.9569E−02 −8.9502E−03 7.3297E−02 4.2408E−02 −4.1372E−02 A6 = 4.2138E−02 2.4262E−02 −2.2068E−03 −2.8902E−02 −5.9246E−02 9.0680E−03 A8 = −1.3436E−02 −8.0066E−03 −7.0854E−03 3.6114E−03 3.4638E−02 −1.1766E−03 A10 = 1.3858E−03 4.0015E−03 2.2934E−03 1.1395E−03 −9.3026E−03 5.3330E−05 A12 = — −7.4029E−04 −1.8598E−04 −4.7956E−04 1.2885E−03 3.5611E−06 A14 = — — — 6.1037E−05 −9.0034E−05 −4.7937E−07 A16 = — — — −2.6308E−06 2.5327E−06 1.4972E−08

In the 4th embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in the following table are the same as those stated in the 1st embodiment with corresponding values for the 4th embodiment, so an explanation in this regard will not be provided again.

Moreover, these parameters can be calculated from Table 7 and Table 8 as the following values and satisfy the following conditions:

4th Embodiment f [mm] 4.94 |f/R7| + |f/R8| 1.02 Fno 2.05 (f/R12) − (f/R11) 5.35 HFOV [deg.] 36.9 f2/f1 0.55 CT5/(T56 + CT6) 1.98 |f/f5| + |f/f6| 5.32 (T34 + T45)/(T12 + T23 + T56) 3.01 TTL/ImgH 1.57 Dr1r6/Dr6r9 0.95 TD/EPD 1.93 (R9 + R10)/(R9 − R10) 0.70

5th Embodiment

FIG. 9 is a schematic view of an image capturing unit according to the 5th embodiment of the present disclosure. FIG. 10 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit according to the 5th embodiment. In FIG. 9, the image capturing unit includes the imaging lens system (its reference numeral is omitted) of the present disclosure and an image sensor 590. The imaging lens system includes, in order from an object side to an image side, an aperture stop 500, a first lens element 510, a second lens element 520, a third lens element 530, a fourth lens element 540, a fifth lens element 550, a sixth lens element 560, an IR-cut filter 570 and an image surface 580, wherein the imaging lens system has a total of six lens elements (510-560) with refractive power. There is an air gap in a paraxial region between any two of the first lens element 510, the second lens element 520, the third lens element 530, the fourth lens element 540, the fifth lens element 550 and the sixth lens element 560 that are adjacent to each other.

The first lens element 510 with positive refractive power has an object-side surface 511 being convex in a paraxial region thereof and an image-side surface 512 being concave in a paraxial region thereof. The first lens element 510 is made of plastic material and has the object-side surface 511 and the image-side surface 512 being both aspheric.

The second lens element 520 with positive refractive power has an object-side surface 521 being convex in a paraxial region thereof and an image-side surface 522 being convex in a paraxial region thereof. The object-side surface 521 of the second lens element 520 has at least one concave shape in an off-axis region thereof. The second lens element 520 is made of plastic material and has the object-side surface 521 and the image-side surface 522 being both aspheric.

The third lens element 530 with negative refractive power has an object-side surface 531 being concave in a paraxial region thereof and an image-side surface 532 being concave in a paraxial region thereof. The third lens element 530 is made of plastic material and has the object-side surface 531 and the image-side surface 532 being both aspheric.

The fourth lens element 540 with positive refractive power has an object-side surface 541 being convex in a paraxial region thereof and an image-side surface 542 being concave in a paraxial region thereof. The image-side surface 542 of the fourth lens element 540 has at least one convex shape in an off-axis region thereof. The fourth lens element 540 is made of plastic material and has the object-side surface 541 and the image-side surface 542 being both aspheric.

The fifth lens element 550 with positive refractive power has an object-side surface 551 being convex in a paraxial region thereof and an image-side surface 552 being convex in a paraxial region thereof. The object-side surface 551 of the fifth lens element 550 has at least one concave shape in an off-axis region thereof. The image-side surface 552 of the fifth lens element 550 has at least one concave shape in an off-axis region thereof. The fifth lens element 550 is made of plastic material and has the object-side surface 551 and the image-side surface 552 being both aspheric.

The sixth lens element 560 with negative refractive power has an object-side surface 561 being concave in a paraxial region thereof and an image-side surface 562 being concave in a paraxial region thereof. The image-side surface 562 of the sixth lens element 560 has at least one convex shape in an off-axis region thereof. The sixth lens element 560 is made of plastic material and has the object-side surface 561 and the image-side surface 562 being both aspheric.

The IR-cut filter 570 is made of glass and located between the sixth lens element 560 and the image surface 580, and will not affect the focal length of the imaging lens system. The image sensor 590 is disposed on or near the image surface 580 of the imaging lens system.

The detailed optical data of the 5th embodiment are shown in Table 9 and the aspheric surface data are shown in Table 10 below.

TABLE 9 5th Embodiment f = 5.01 mm, Fno = 2.05, HFOV = 36.6 deg. Curvature Focal Surface # Radius Thickness Material Index Abbe # Length 0 Object Plano Infinity 1 Ape. Stop Plano −0.378   2 Lens 1 2.047 (ASP) 0.480 Plastic 1.544 55.9 7.28 3 3.887 (ASP) 0.190 4 Lens 2 4.060 (ASP) 0.514 Plastic 1.544 55.9 5.02 6 −7.955 (ASP) 0.050 7 Lens 3 −11.523 (ASP) 0.336 Plastic 1.639 23.5 −4.60 8 3.987 (ASP) 0.393 9 Lens 4 13.882 (ASP) 0.677 Plastic 1.639 23.5 62.15 10 20.937 (ASP) 0.572 11 Lens 5 6.392 (ASP) 0.837 Plastic 1.544 55.9 2.84 12 −1.942 (ASP) 0.268 13 Lens 6 −4.079 (ASP) 0.430 Plastic 1.544 55.9 −2.13 14 1.674 (ASP) 0.600 15 IR-cut filter Plano 0.210 Glass 1.517 64.2 — 16 Plano 0.453 17 Image Plano — Note: Reference wavelength is 587.6 nm (d-line).

TABLE 10 Aspheric Coefficients Surface # 2 3 4 5 6 7 k = 3.4342E−01 3.4967E+00 −4.9430E+01 −9.2927E+00 −6.6997E+01 7.3469E+00 A4 = −1.3228E−02 −5.7295E−02 5.5981E−03 −8.4910E−02 −4.2347E−02 −2.9269E−02 A6 = 2.6473E−04 −1.2192E−02 −1.2731E−01 7.3832E−02 1.4122E−01 8.1401E−02 A8 = −6.4689E−03 1.4322E−02 1.1598E−01 −5.3483E−02 −1.6225E−01 −1.0496E−01 A10 = 2.6542E−03 — −3.4794E−02 1.5058E−02 6.9929E−02 5.2584E−02 A12 = — — — −2.3902E−03 −9.0051E−03 −9.3561E−03 Surface # 8 9 10 11 12 13 k = 6.7084E+01 −3.9939E+01 −9.0000E+01 −8.8133E+00 7.3910E−01 −9.7061E+00 A4 = −8.0610E−02 −7.5871E−02 2.9015E−02 4.4764E−02 −1.1972E−02 −4.0121E−02 A6 = 4.5527E−02 2.6096E−02 −2.2363E−02 4.9392E−03 6.4049E−03 1.1786E−02 A8 = −1.5770E−02 −6.2062E−03 7.3221E−03 −9.0051E−03 −2.5059E−04 −2.6714E−03 A10 = 2.8922E−03 2.4345E−03 −2.7591E−03 2.3730E−03 −6.0510E−05 3.4411E−04 A12 = −6.1153E−04 −4.3195E−04 5.4624E−04 −2.6497E−04 5.0843E−06 −2.2384E−05 A14 = — — −3.6642E−05 1.1111E−05 — 5.7373E−07

In the 5th embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in the following table are the same as those stated in the 1st embodiment with corresponding values for the 5th embodiment, so an explanation in this regard will not be provided again.

Moreover, these parameters can be calculated from Table 9 and Table 10 as the following values and satisfy the following conditions:

5th Embodiment f [mm] 5.01 |f/R7| + |f/R8| 0.60 Fno 2.05 (f/R12) − (f/R11) 4.22 HFOV [deg.] 36.6 f2/f1 0.69 CT5/(T56 + CT6) 1.20 |f/f5| + |f/f6| 4.12 (T34 + T45)/(T12 + T23 + T56) 1.90 TTL/ImgH 1.59 Dr1r6/Dr6r9 0.96 TD/EPD 1.94 (R9 + R10)/(R9 − R10) 0.53

6th Embodiment

FIG. 11 is a schematic view of an image capturing unit according to the 6th embodiment of the present disclosure. FIG. 12 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit according to the 6th embodiment. In FIG. 11, the image capturing unit includes the imaging lens system (its reference numeral is omitted) of the present disclosure and an image sensor 690. The imaging lens system includes, in order from an object side to an image side, an aperture stop 600, a first lens element 610, a second lens element 620, a third lens element 630, a fourth lens element 640, a fifth lens element 650, a sixth lens element 660, an IR-cut filter 670 and an image surface 680, wherein the imaging lens system has a total of six lens elements (610-660) with refractive power. There is an air gap in a paraxial region between any two of the first lens element 610, the second lens element 620, the third lens element 630, the fourth lens element 640, the fifth lens element 650 and the sixth lens element 660 that are adjacent to each other.

The first lens element 610 with positive refractive power has an object-side surface 611 being convex in a paraxial region thereof and an image-side surface 612 being concave in a paraxial region thereof. The first lens element 610 is made of plastic material and has the object-side surface 611 and the image-side surface 612 being both aspheric.

The second lens element 620 with positive refractive power has an object-side surface 621 being convex in a paraxial region thereof and an image-side surface 622 being convex in a paraxial region thereof. The object-side surface 621 of the second lens element 620 has at least one concave shape in an off-axis region thereof. The second lens element 620 is made of plastic material and has the object-side surface 621 and the image-side surface 622 being both aspheric.

The third lens element 630 with negative refractive power has an object-side surface 631 being concave in a paraxial region thereof and an image-side surface 632 being concave in a paraxial region thereof. The third lens element 630 is made of plastic material and has the object-side surface 631 and the image-side surface 632 being both aspheric.

The fourth lens element 640 with positive refractive power has an object-side surface 641 being convex in a paraxial region thereof and an image-side surface 642 being concave in a paraxial region thereof. The image-side surface 642 of the fourth lens element 640 has at least one convex shape in an off-axis region thereof. The fourth lens element 640 is made of plastic material and has the object-side surface 641 and the image-side surface 642 being both aspheric.

The fifth lens element 650 with positive refractive power has an object-side surface 651 being convex in a paraxial region thereof and an image-side surface 652 being convex in a paraxial region thereof. The object-side surface 651 of the fifth lens element 650 has at least one concave shape in an off-axis region thereof. The image-side surface 652 of the fifth lens element 650 has at least one concave shape in an off-axis region thereof. The fifth lens element 650 is made of plastic material and has the object-side surface 651 and the image-side surface 652 being both aspheric.

The sixth lens element 660 with negative refractive power has an object-side surface 661 being concave in a paraxial region thereof and an image-side surface 662 being concave in a paraxial region thereof. The image-side surface 662 of the sixth lens element 660 has at least one convex shape in an off-axis region thereof. The sixth lens element 660 is made of plastic material and has the object-side surface 661 and the image-side surface 662 being both aspheric.

The IR-cut filter 670 is made of glass and located between the sixth lens element 660 and the image surface 680, and will not affect the focal length of the imaging lens system. The image sensor 690 is disposed on or near the image surface 680 of the imaging lens system.

The detailed optical data of the 6th embodiment are shown in Table 11 and the aspheric surface data are shown in Table 12 below.

TABLE 11 6th Embodiment f = 5.09 mm, Fno = 2.05, HFOV = 36.0 deg. Curvature Focal Surface # Radius Thickness Material Index Abbe # Length 0 Object Plano Infinity 1 Ape. Stop Plano −0.395   2 Lens 1 2.066 (ASP) 0.481 Plastic 1.544 55.9 7.14 3 4.050 (ASP) 0.220 4 Lens 2 4.189 (ASP) 0.536 Plastic 1.544 55.9 4.63 5 −6.048 (ASP) 0.050 6 Lens 3 −9.576 (ASP) 0.322 Plastic 1.639 23.5 −4.38 7 4.001 (ASP) 0.415 8 Lens 4 21.870 (ASP) 0.800 Plastic 1.639 23.5 120.35 9 30.125 (ASP) 0.539 10 Lens 5 6.152 (ASP) 0.724 Plastic 1.544 55.9 3.08 11 −2.206 (ASP) 0.332 12 Lens 6 −2.715 (ASP) 0.430 Plastic 1.544 55.9 −2.25 13 2.350 (ASP) 0.600 14 IR-cut filter Plano 0.210 Glass 1.517 64.2 — 15 Plano 0.392 16 Image Plano — Note: Reference wavelength is 587.6 nm (d-line). Effective radius of the image-side surface of the second lens element (surface 5) is 1.290 mm.

TABLE 12 Aspheric Coefficients Surface # 2 3 4 5 6 7 k = 4.4801E−01 7.0126E+00 −4.2914E+01 −3.7070E+01 −8.9992E+01 4.5837E+00 A4 = −1.2204E−02 −4.2678E−02 1.6566E−02 −2.2633E−02 1.8004E−02 −6.0195E−03 A6 = −2.2567E−03 −8.5705E−03 −7.4744E−02 −1.7651E−02 1.2179E−02 2.5721E−02 A8 = −3.0392E−03 6.3871E−03 5.3438E−02 −6.4789E−03 −5.3442E−02 −3.2083E−02 A10 = 1.3542E−03 — −1.4860E−02 1.0427E−02 3.6053E−02 1.2864E−02 A12 = — — — −3.7063E−03 −6.7525E−03 — Surface # 8 9 10 11 12 13 k = 6.7878E+01 −3.9939E+01 −9.0000E+01 −8.7895E+00 −1.8394E−01 −1.4255E+01 A4 = −5.8345E−02 −6.4335E−02 1.9084E−02 2.2891E−02 9.9049E−03 −2.9962E−02 A6 = 2.6571E−02 1.9470E−02 −1.5128E−02 1.9838E−02 8.8569E−04 7.3102E−03 A8 = −7.7902E−03 −4.3003E−03 3.8619E−03 −1.4747E−02 9.3972E−04 −1.5144E−03 A10 = 2.8116E−04 1.5887E−03 −1.8349E−03 3.6089E−03 −1.9870E−04 1.7208E−04 A12 = — −2.4261E−04 4.1490E−04 −3.9937E−04 1.1865E−05 −9.6939E−06 A14 = — — −2.8595E−05 1.6842E−05 — 2.1755E−07

In the 6th embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in the following table are the same as those stated in the 1st embodiment with corresponding values for the 6th embodiment, so an explanation in this regard will not be provided again.

Moreover, these parameters can be calculated from Table 11 and Table 12 as the following values and satisfy the following conditions:

6th Embodiment f [mm] 5.09 |f/R7| + |f/R8| 0.40 Fno 2.05 (f/R12) − (f/R11) 4.04 HFOV [deg.] 36.0 f2/f1 0.65 CT5/(T56 + CT6) 0.95 |f/f5| + |f/f6| 3.91 (T34 + T45)/(T12 + T23 + T56) 1.58 TTL/ImgH 1.60 Dr1r6/Dr6r9 0.92 TD/EPD 1.95 (R9 + R10)/(R9 − R10) 0.47

7th Embodiment

FIG. 13 is a schematic view of an image capturing unit according to the 7th embodiment of the present disclosure. FIG. 14 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit according to the 7th embodiment. In FIG. 13, the image capturing unit includes the imaging lens system (its reference numeral is omitted) of the present disclosure and an image sensor 790. The imaging lens system includes, in order from an object side to an image side, a first lens element 710, a second lens element 720, an aperture stop 700, a third lens element 730, a fourth lens element 740, a fifth lens element 750, a sixth lens element 760, an IR-cut filter 770 and an image surface 780, wherein the imaging lens system has a total of six lens elements (710-760) with refractive power. There is an air gap in a paraxial region between any two of the first lens element 710, the second lens element 720, the third lens element 730, the fourth lens element 740, the fifth lens element 750 and the sixth lens element 760 that are adjacent to each other.

The first lens element 710 with positive refractive power has an object-side surface 711 being convex in a paraxial region thereof and an image-side surface 712 being concave in a paraxial region thereof. The first lens element 710 is made of plastic material and has the object-side surface 711 and the image-side surface 712 being both aspheric.

The second lens element 720 with positive refractive power has an object-side surface 721 being convex in a paraxial region thereof and an image-side surface 722 being concave in a paraxial region thereof. The object-side surface 721 of the second lens element 720 has at least one concave shape in an off-axis region thereof. The second lens element 720 is made of plastic material and has the object-side surface 721 and the image-side surface 722 being both aspheric.

The third lens element 730 with negative refractive power has an object-side surface 731 being convex in a paraxial region thereof and an image-side surface 732 being concave in a paraxial region thereof. The third lens element 730 is made of plastic material and has the object-side surface 731 and the image-side surface 732 being both aspheric.

The fourth lens element 740 with positive refractive power has an object-side surface 741 being convex in a paraxial region thereof and an image-side surface 742 being concave in a paraxial region thereof. The image-side surface 742 of the fourth lens element 740 has at least one convex shape in an off-axis region thereof. The fourth lens element 740 is made of plastic material and has the object-side surface 741 and the image-side surface 742 being both aspheric.

The fifth lens element 750 with positive refractive power has an object-side surface 751 being convex in a paraxial region thereof and an image-side surface 752 being convex in a paraxial region thereof. The object-side surface 751 of the fifth lens element 750 has at least one concave shape in an off-axis region thereof. The image-side surface 752 of the fifth lens element 750 has at least one concave shape in an off-axis region thereof. The fifth lens element 750 is made of plastic material and has the object-side surface 751 and the image-side surface 752 being both aspheric.

The sixth lens element 760 with negative refractive power has an object-side surface 761 being concave in a paraxial region thereof and an image-side surface 762 being concave in a paraxial region thereof. The image-side surface 762 of the sixth lens element 760 has at least one convex shape in an off-axis region thereof. The sixth lens element 760 is made of plastic material and has the object-side surface 761 and the image-side surface 762 being both aspheric.

The IR-cut filter 770 is made of glass and located between the sixth lens element 760 and the image surface 780, and will not affect the focal length of the imaging lens system. The image sensor 790 is disposed on or near the image surface 780 of the imaging lens system.

The detailed optical data of the 7th embodiment are shown in Table 13 and the aspheric surface data are shown in Table 14 below.

TABLE 13 7th Embodiment f = 5.02 mm, Fno = 2.25, HFOV = 36.1 deg. Curvature Focal Surface # Radius Thickness Material Index Abbe # Length 0 Object Plano Infinity 1 Lens 1 2.145 (ASP) 0.422 Plastic 1.544 55.9 502.16 2 2.012 (ASP) 0.058 3 Lens 2 1.801 (ASP) 0.529 Plastic 1.570 57.0 3.31 4 35.744 (ASP) 0.009 5 Ape. Stop Plano 0.041 6 Lens 3 68.750 (ASP) 0.300 Plastic 1.639 23.5 −6.55 7 3.936 (ASP) 0.664 8 Lens 4 8.062 (ASP) 0.398 Plastic 1.639 23.5 154.55 9 8.609 (ASP) 0.701 10 Lens 5 9.201 (ASP) 1.208 Plastic 1.570 57.0 2.27 11 −1.436 (ASP) 0.050 12 Lens 6 −4.368 (ASP) 0.450 Plastic 1.570 57.0 −1.77 13 1.361 (ASP) 0.600 14 IR-cut filter Plano 0.300 Glass 1.517 64.2 — 15 Plano 0.321 16 Image Plano — Note: Reference wavelength is 587.6 nm (d-line).

TABLE 14 Aspheric Coefficients Surface # 1 2 3 4 6 7 k = −1.3983E−01 −5.5598E+00 −8.5113E+00 −1.0000E+00 9.0000E+01 9.2503E+00 A4 = −2.3124E−02 −1.0332E−01 2.9122E−02 −4.8303E−02 −4.5611E−02 −1.6929E−02 A6 = −2.2698E−03 2.4343E−02 −1.1436E−01 6.3024E−02 1.3384E−01 7.2348E−02 A8 = 1.8069E−03 8.3875E−03 1.2437E−01 −5.6175E−02 −1.3707E−01 −9.9469E−02 A10 = −4.9032E−03 7.9787E−03 −4.9634E−02 −5.3081E−03 6.6686E−02 7.2624E−02 A12 = −3.6837E−04 −8.3822E−03 5.0324E−03 3.7898E−02 −4.0774E−03 −2.4646E−02 A14 = 2.9144E−03 2.9050E−03 1.5270E−03 −2.0934E−02 −5.1825E−03 1.2150E−03 A16 = −8.3079E−04 7.0710E−06 1.7042E−07 3.4646E−03 7.8428E−04 5.2802E−04 Surface # 8 9 10 11 12 13 k = 1.0920E+01 1.6412E+01 5.0501E+00 −9.1952E+00 9.0882E−01 −9.3590E+00 A4 = −8.4711E−02 −8.2970E−02 −2.5637E−02 −4.3336E−03 −1.4765E−02 −3.7977E−02 A6 = 9.3727E−02 7.1166E−02 2.2558E−02 3.7423E−02 2.1342E−02 1.3185E−02 A8 = −1.6978E−01 −9.3476E−02 −1.9157E−02 −1.9304E−02 −7.1430E−03 −3.6532E−03 A10 = 1.8044E−01 7.4627E−02 7.3993E−03 4.1159E−03 1.3820E−03 6.2090E−04 A12 = −1.1504E−01 −3.5803E−02 −2.0435E−03 −3.9265E−04 −1.5406E−04 −5.9052E−05 A14 = 3.9709E−02 9.5109E−03 3.6138E−04 9.3772E−06 8.6717E−06 2.8695E−06 A16 = −5.7245E−03 −1.0558E−03 −2.6545E−05 5.1289E−07 −1.7744E−07 −5.5520E−08

In the 7th embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in the following table are the same as those stated in the 1st embodiment with corresponding values for the 7th embodiment, so an explanation in this regard will not be provided again.

Moreover, these parameters can be calculated from Table 13 and Table 14 as the following values and satisfy the following conditions:

7th Embodiment f [mm] 5.02 |f/R7| + |f/R8| 1.21 Fno 2.25 (f/R12) − (f/R11) 4.84 HFOV [deg.] 36.1 f2/f1 0.01 CT5/(T56 + CT6) 2.42 |f/f5| + |f/f6| 5.05 (T34 + T45)/(T12 + T23 + T56) 8.64 TTL/ImgH 1.59 Dr1r6/Dr6r9 0.77 TD/EPD 2.16 (R9 + R10)/(R9 − R10) 0.73

8th Embodiment

FIG. 15 is a schematic view of an image capturing unit according to the 8th embodiment of the present disclosure. FIG. 16 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit according to the 8th embodiment. In FIG. 15, the image capturing unit includes the imaging lens system (its reference numeral is omitted) of the present disclosure and an image sensor 890. The imaging lens system includes, in order from an object side to an image side, an aperture stop 800, a first lens element 810, a second lens element 820, a third lens element 830, a fourth lens element 840, a fifth lens element 850, a sixth lens element 860, an IR-cut filter 870 and an image surface 880, wherein the imaging lens system has a total of six lens elements (810-860) with refractive power. There is an air gap in a paraxial region between any two of the first lens element 810, the second lens element 820, the third lens element 830, the fourth lens element 840, the fifth lens element 850 and the sixth lens element 860 that are adjacent to each other.

The first lens element 810 with positive refractive power has an object-side surface 811 being convex in a paraxial region thereof and an image-side surface 812 being concave in a paraxial region thereof. The first lens element 810 is made of plastic material and has the object-side surface 811 and the image-side surface 812 being both aspheric.

The second lens element 820 with positive refractive power has an object-side surface 821 being convex in a paraxial region thereof and an image-side surface 822 being convex in a paraxial region thereof. The object-side surface 821 of the second lens element 820 has at least one concave shape in an off-axis region thereof. The second lens element 820 is made of plastic material and has the object-side surface 821 and the image-side surface 822 being both aspheric.

The third lens element 830 with negative refractive power has an object-side surface 831 being concave in a paraxial region thereof and an image-side surface 832 being concave in a paraxial region thereof. The third lens element 830 is made of plastic material and has the object-side surface 831 and the image-side surface 832 being both aspheric.

The fourth lens element 840 with negative refractive power has an object-side surface 841 being concave in a paraxial region thereof and an image-side surface 842 being concave in a paraxial region thereof. The image-side surface 842 of the fourth lens element 840 has at least one convex shape in an off-axis region thereof. The fourth lens element 840 is made of plastic material and has the object-side surface 841 and the image-side surface 842 being both aspheric.

The fifth lens element 850 with positive refractive power has an object-side surface 851 being convex in a paraxial region thereof and an image-side surface 852 being convex in a paraxial region thereof. The object-side surface 851 of the fifth lens element 850 has at least one concave shape in an off-axis region thereof. The image-side surface 852 of the fifth lens element 850 has at least one concave shape in an off-axis region thereof. The fifth lens element 850 is made of plastic material and has the object-side surface 851 and the image-side surface 852 being both aspheric.

The sixth lens element 860 with negative refractive power has an object-side surface 861 being concave in a paraxial region thereof and an image-side surface 862 being concave in a paraxial region thereof. The image-side surface 862 of the sixth lens element 860 has at least one convex shape in an off-axis region thereof. The sixth lens element 860 is made of plastic material and has the object-side surface 861 and the image-side surface 862 being both aspheric.

The IR-cut filter 870 is made of glass and located between the sixth lens element 860 and the image surface 880, and will not affect the focal length of the imaging lens system. The image sensor 890 is disposed on or near the image surface 880 of the imaging lens system.

The detailed optical data of the 8th embodiment are shown in Table 15 and the aspheric surface data are shown in Table 16 below.

TABLE 15 8th Embodiment f = 3.75 mm, Fno = 2.06, HFOV = 37.6 deg. Curvature Focal Surface # Radius Thickness Material Index Abbe # Length 0 Object Plano Infinity 1 Ape. Stop Plano −0.236 2 Lens 1 1.636 (ASP) 0.356 Plastic 1.544 55.9 5.66 3 3.223 (ASP) 0.144 4 Lens 2 3.768 (ASP) 0.578 Plastic 1.544 55.9 4.37 5 −6.106 (ASP) 0.050 6 Lens 3 −8.507 (ASP) 0.250 Plastic 1.639 23.5 −4.98 7 5.136 (ASP) 0.381 8 Lens 4 −67.955 (ASP) 0.304 Plastic 1.639 23.5 −63.57 9 101.170 (ASP) 0.323 10 Lens 5 2.943 (ASP) 0.425 Plastic 1.544 55.9 1.79 11 −1.382 (ASP) 0.095 12 Lens 6 −2.067 (ASP) 0.400 Plastic 1.544 55.9 −1.42 13 1.323 (ASP) 0.500 14 IR-cut filter Plano 0.300 Glass 1.517 64.2 — 15 Plano 0.383 16 Image Plano — Note: Reference wavelength is 587.6 nm (d-line).

TABLE 16 Aspheric Coefficients Surface # 2 3 4 5 6 7 k = 1.0220E−01 8.4654E+00 −9.0000E+01 −1.9183E+01 2.5246E+01 −9.0000E+01 A4 = −3.3271E−02 −1.2468E−01 8.9236E−02 −3.3640E−01 −2.9575E−01 2.6630E−02 A6 = −1.0104E−02 2.4856E−03 −3.9396E−01 3.4291E−01 4.4375E−01 6.4214E−02 A8 = −1.6348E−02 −4.6428E−02 6.1178E−01 −2.9587E−01 −5.1248E−01 −1.9209E−01 A10 = — 4.0385E−02 −5.4721E−01 1.3032E−01 4.0005E−01 1.7422E−01 A12 = — — 2.1381E−01 −2.3333E−02 −1.1132E−01 −4.8291E−02 Surface # 8 9 10 11 12 13 k = 9.0000E+01 −4.1439E+01 −6.8931E+01 −6.8621E+00 −1.1737E−01 −1.0202E+01 A4 = −1.9175E−01 −3.4861E−01 5.5318E−02 1.8592E−01 5.3952E−02 −1.0746E−01 A6 = 1.8507E−01 3.5023E−01 −1.8699E−01 2.4604E−02 3.5706E−02 7.7066E−02 A8 = −1.0489E−01 −3.5701E−01 8.6065E−02 −1.9576E−01 −3.5899E−02 −5.1118E−02 A10 = −8.7397E−02 3.7095E−01 9.5899E−03 1.2586E−01 1.3782E−02 2.0950E−02 A12 = 3.2644E−02 −3.1350E−01 −6.8885E−02 −3.9562E−02 −2.3748E−03 −4.9039E−03 A14 = — 1.1318E−01 2.6564E−02 7.4733E−03 1.5733E−04 5.9808E−04 A16 = — — — −7.0271E−04 — −2.9555E−05

In the 8th embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in the following table are the same as those stated in the 1st embodiment with corresponding values for the 8th embodiment, so an explanation in this regard will not be provided again.

Moreover, these parameters can be calculated from Table 15 and Table 16 as the following values and satisfy the following conditions:

8th Embodiment f [mm] 3.75 |f/R7| + |f/R8| 0.09 Fno 2.06 (f/R12) − (f/R11) 4.65 HFOV [deg.] 37.6 f2/f1 0.77 CT5/(T56 + CT6) 0.86 |f/f5| + |f/f6| 4.74 (T34 + T45)/(T12 + T23 + T56) 2.44 TTL/ImgH 1.50 Dr1r6/Dr6r9 1.37 TD/EPD 1.82 (R9 + R10)/(R9 − R10) 0.36

The foregoing image capturing unit is able to be installed in, but not limited to, an electronic device, including smart phones, tablet personal computers and wearable apparatus. According to the present disclosure, both of the first lens element and the second lens element have positive refractive power. Therefore, it is favorable for avoiding overloading the positive refractive power on the lens element close to the object side so as to reduce the sensitivity of the imaging lens system. The object-side surface of the fifth lens element is convex in a paraxial region thereof. Therefore, it is favorable for avoiding the fifth lens element having high thickness ratio.

The foregoing description, for the purpose of explanation, has been described with reference to specific embodiments. It is to be noted that TABLES 1-16 show different data of the different embodiments; however, the data of the different embodiments are obtained from experiments. The embodiments were chosen and described in order to best explain the principles of the disclosure and its practical applications, to thereby enable others skilled in the art to best utilize the disclosure and various embodiments with various modifications as are suited to the particular use contemplated. The embodiments depicted above and the appended drawings are exemplary and are not intended to be exhaustive or to limit the scope of the present disclosure to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. 

What is claimed is:
 1. An imaging lens system comprising, in order from an object side to an image side: a first lens element with positive refractive power having an object-side surface being convex; a second lens element having positive refractive power; a third lens element having an object-side surface being convex; a fourth lens element with positive refractive power having an object-side surface being convex; a fifth lens element having an object-side surface being convex; and a sixth lens element having an image-side surface being concave in a paraxial region thereof, wherein the image-side surface of the sixth lens element has at least one convex shape in an off-axis region thereof, and an object-side surface and the image-side surface of the sixth lens element are both aspheric; wherein the imaging lens system has a total of six lens elements, an air gap in a paraxial region is between any two of the first lens element, the second lens element, the third lens element, the fourth lens element, the fifth lens element and the sixth lens element that are adjacent to each other, and an axial distance between the first lens element and the second lens element is larger than an axial distance between the fifth lens element and the sixth lens element; wherein a focal length of the first lens element is f1, a focal length of the second lens element is f2, an axial distance between the object-side surface of the first lens element and an image surface is TTL, a maximum image height of the imaging lens system is ImgH, and the following conditions are satisfied: f2/f|<1.60; and TTL/ImgH<3.0.
 2. The imaging lens system of claim 1, wherein the second lens element has an object-side surface being convex.
 3. The imaging lens system of claim 2, further comprising an aperture stop disposed between an imaged object and the third lens element.
 4. The imaging lens system of claim 3, wherein the first lens element has an image-side surface being concave.
 5. The imaging lens system of claim 1, wherein a central thickness of the fifth lens element is larger than a central thickness of the sixth lens element.
 6. The imaging lens system of claim 1, wherein a focal length of the imaging lens system is f, a focal length of the fifth lens element is f5, a focal length of the sixth lens element is f6, and the following condition is satisfied: 3.0<|f/f5|+|f/f6|<7.5.
 7. The imaging lens system of claim 1, wherein the third lens element has negative refractive power, and the third lens element has an image-side surface being concave.
 8. The imaging lens system of claim 1, wherein the sixth lens element has negative refractive power.
 9. The imaging lens system of claim 1, wherein an axial distance between the object-side surface of the first lens element and the image-side surface of the sixth lens element is TD, an entrance pupil diameter of the imaging lens system is EPD, and the following condition is satisfied: TD/EPD<2.50.
 10. The imaging lens system of claim 1, wherein the fifth lens element has an image-side surface having at least one inflection point in an off-axis region thereof.
 11. The imaging lens system of claim 1, wherein a central thickness of the fifth lens element is CT5, a central thickness of the sixth lens element is CT6, the axial distance between the fifth lens element and the sixth lens element is T56, and the following condition is satisfied: 0.70<CT5/(T56+CT6).
 12. The imaging lens system of claim 1, wherein the axial distance between the first lens element and the second lens element is T12, an axial distance between the second lens element and the third lens element is T23, an axial distance between the third lens element and the fourth lens element is T34, an axial distance between the fourth lens element and the fifth lens element is T45, the axial distance between the fifth lens element and the sixth lens element is T56, and the following condition is satisfied: 1.5<(T34+T45)/(T12+T23+T56).
 13. An image capturing unit, comprising: the imaging lens system of claim 1; and an image sensor, wherein the image sensor is disposed on the image side of the imaging lens system.
 14. An electronic device, comprising: the image capturing unit of claim
 13. 15. An imaging lens system comprising, in order from an object side to an image side: a first lens element with positive refractive power having an object-side surface being convex; a second lens element with positive refractive power having an image-side surface being convex; a third lens element; a fourth lens element having an object-side surface being convex; a fifth lens element; and a sixth lens element having an image-side surface being concave in a paraxial region thereof, wherein the image-side surface of the sixth lens element has at least one convex shape in an off-axis region thereof, and an object-side surface and the image-side surface of the sixth lens element are both aspheric; wherein the imaging lens system has a total of six lens elements, an air gap in a paraxial region is between any two of the first lens element, the second lens element, the third lens element, the fourth lens element, the fifth lens element and the sixth lens element that are adjacent to each other, and a central thickness of the fifth lens element is larger than a central thickness of the sixth lens element; wherein a focal length of the imaging lens system is f, a focal length of the first lens element is f1, a focal length of the second lens element is f2, an axial distance between the object-side surface of the first lens element and an image surface is TTL, a maximum image height of the imaging lens system is ImgH, a curvature radius of the object-side surface of the fourth lens element is R7, a curvature radius of an image-side surface of the fourth lens element is R8, an axial distance between the object-side surface of the first lens element and the image-side surface of the sixth lens element is TD, an entrance pupil diameter of the imaging lens system is EPD, and the following conditions are satisfied: TD/EPD≦1.95; f2/f1≦0.69; TTL/ImgH<3.0; and |f/R7|+|f/R8|<0.80.
 16. The imaging lens system of claim 15, wherein the second has an object-side surface being convex.
 17. The imaging lens system of claim 15, further comprising an aperture stop disposed between an imaged object and the third lens element.
 18. The imaging lens system of claim 15, wherein the first lens element has an image-side surface being concave.
 19. The imaging lens system of claim 15, wherein the focal length of the imaging lens system is f, a focal length of the fifth lens element is f5, a focal length of the sixth lens element is f6, and the following condition is satisfied: 3.0<|f/f5|+|f/f6|<7.5.
 20. The imaging lens system of claim 15, wherein the third lens element has negative refractive power.
 21. The imaging lens system of claim 15, wherein the sixth lens element has negative refractive power.
 22. The imaging lens system of claim 15, wherein the fifth lens element has an image-side surface having at least one inflection point in an off-axis region thereof.
 23. The imaging lens system of claim 15, wherein the central thickness of the fifth lens element is CT5, the central thickness of the sixth lens element is CT6, an axial distance between the fifth lens element and the sixth lens element is T56, and the following condition is satisfied: 0.70<CT5/(T56+CT6).
 24. The imaging lens system of claim 15, wherein an axial distance between the object-side surface of the first lens element and an image-side surface of the third lens element is Dr1r6, an axial distance between the image-side surface of the third lens element and an object-side surface of the fifth lens element is Dr6r9, and the following condition is satisfied: 0.8<Dr1r6/Dr6r9<1.2.
 25. The imaging lens system of claim 15, wherein an axial distance between the first lens element and the second lens element is T12, an axial distance between the second lens element and the third lens element is T23, an axial distance between the third lens element and the fourth lens element is T34, an axial distance between the fourth lens element and the fifth lens element is T45, an axial distance between the fifth lens element and the sixth lens element is T56, and the following condition is satisfied: 1.5<(T34+T45)/(T12+T23+T56).
 26. An image capturing unit, comprising: the imaging lens system of claim 15; and an image sensor, wherein the image sensor is disposed on the image side of the imaging lens system.
 27. An electronic device, comprising: the image capturing unit of claim
 26. 